Vidauban: Clay Soil, Subsidence and Cracks – Official Data

What characterises Vidauban in building surveys

In Vidauban, we regularly record structural damage that is no accident: the commune stretches between the first wooded relief of pines and cork oaks towards the Massif des Maures and the clay-silt plain carved out by the Argens – two soil configurations highly reactive to wetting-drying cycles. I work there as much on Provençal villas from the 70s-80s, built on lightly reinforced shallow foundations to the standards of the time, as on more recent houses from the estates that have multiplied around the old centre over the last twenty years, sometimes built too quickly on backfilled ground with no thorough soil survey. In both cases, the common factor remains the clayey, swelling nature of the local subsoil, which shrinks sharply during dry summers and regains volume with the first autumn rains, generating differential settlement under building corners and load points. The large trees and pines planted too close to the walls, very common in Vidauban gardens, further aggravate the phenomenon by drying out the soil at depth. It is this combination – sensitive clay, sometimes undersized foundations and thirsty vegetation – that explains why so many façade cracks and slab separations are found in this area.

Rainfall: the commune’s long memory

The area’s weather archives cover 35 complete years (1991-2025). The driest ever recorded: 2007, with 393 mm over the year, against a local average of 746 mm. 2022 ranks as the 9th driest year out of 35 (562 mm against an average of 746 mm); 2023 follows in 12th place (598 mm).

This ranking gives the true measure of the recent sequence: when the years 2020-2023 sit high up the list of dry years, the clay has had no time to rehydrate between episodes – the textbook scenario for delayed cracking. The reverse is just as instructive: a very wet year following an exceptional drought triggers abrupt swelling of the ground.

Damp, water ingress and rising damp in Vidauban

Damp in a wall can have four causes – rising damp, water ingress, condensation or a leak – and the treatments are completely different depending on the origin.

If you contact us from Vidauban about a damp stain, you may already have read online that resin injections are needed, or a mechanical ventilation system. My message: not so fast. Before treating, the exact cause must be identified – otherwise the money spent solves nothing.

The 4 causes and how to recognise them

• Rising damp: water from the ground rises into the wall by capillary action. A horizontal mark at the foot of the wall, often over 1 to 1.5 m, that worsens with the age of the building and the absence of a damp-proof course.
• Water ingress: water enters from outside (roof, façade, joinery, terrace). The stains appear after rain, often localised near a specific point (window, gutter, joint).
• Condensation: moisture in the air settles on a cold surface through poor ventilation. Typical in bathrooms or poorly aired rooms, with mould at cold points (corners, thermal bridges).
• Leak: a defective pipe or drain. A localised stain, sometimes evolving over time, independent of the weather outside.

The trap of the diagnosis sold by the treatment contractor

Many companies selling damp treatments carry out the diagnosis themselves before proposing their solution. The problem: they have a direct commercial interest in steering the diagnosis towards the cause that justifies their service – often rising damp, more profitable in injections. The result, in Vidauban as elsewhere: I have seen water ingress or condensation problems wrongly treated by resin injection, with no effect whatsoever on the real damp.

An independent diagnosis, with no sale of works behind it, identifies the true origin before money is committed. For Vidauban, you can contact me for an independent diagnosis. You will also find more detail in my damp guide for 06, 83 and 13.

Vidauban: drought, clay and cracks – what the official figures say, and what you should do with them

Your house in Vidauban is cracking and you want to know whether it is linked to drought: the GASPAR database records 6 drought prefectoral decrees in the commune (2000, 2004, 2018, 2020, 2023, 2024) and 15 flood decrees, i.e. 21 natural disaster declarations (Cat Nat). Local rainfall confirms the scenario: three dry years in a row (2020, 2022, 2023), then a rebound to 1,015 mm in 2024 – exactly the mechanism that eventually opens up foundations in the plain of the Maures. If your cracks date from 2021 to today, keep this page: it tells you what to check and with whom.

Cassini Expertise, an independent building expert, handles cracks and drought-related damage in Vidauban and throughout the Var. This page brings together the commune’s official data, point by point, and what they mean for you in practice.

Natural disaster declarations (Cat Nat) in Vidauban: which period should your cracks be tied to?

The GASPAR database (decrees published in the Journal officiel since 1982) records 21 natural disaster declarations (Cat Nat) for the commune of Vidauban:

• 6 drought prefectoral decrees (differential ground movement linked to clay shrink-swell (RGA))
  • event of 01/06/1998 (prefectoral decree of 27/12/2000)
  • event of 01/01/2002 (prefectoral decree of 25/08/2004)
  • event of 01/07/2017 (prefectoral decree of 18/09/2018)
  • event of 01/07/2019 (prefectoral decree of 15/12/2020)
  • event of 01/04/2022 (prefectoral decree of 03/04/2023)
  • event of 01/04/2023 (prefectoral decree of 18/06/2024)
• 15 flood prefectoral decrees and storm

First thing to do: find the date your cracks appeared (photos, neighbours’ accounts, purchase date) and compare it with these periods. If it matches one of them, you can claim natural disaster declaration (Cat Nat) compensation – provided you declared the loss to your insurer within 30 days of publication of the decree. If the deadline has passed, or the period matches no decree, the route of a claim against the seller for hidden defect (vice caché) or fraud (dol) remains: keep all documents (deeds, surveys, dated photos).

The official exposure to clay shrink-swell (RGA): what to check before buying or building

The GéoRisques platform (BRGM) classifies Vidauban at medium exposure to clay shrink-swell (RGA). This is the level your insurer and your notaire already look at to assess the risk on a plot – you can consult it yourself on georisques.gouv.fr by entering the property’s address. Also worth noting: radon potential class 3 across the commune (IRSN/GéoRisques data), a point to check with a detector if you spend time in a basement or on the ground floor.

This classification completes the decree history above: the hazard rating says what can happen, the decrees say what has already happened. A house rated “medium exposure” that has come through one or more dry summers deserves a careful look at any cracks, even discreet ones.

Forty years of decrees: the full chronology for Vidauban

Each line = an event recognised by an interministerial decree published in the Journal officiel (GASPAR database):

• 🔵 08/1983 → 08/1983 – Floods (prefectoral decree of 15/11/1983)
• 🔵 09/1992 → 09/1992 – Floods (prefectoral decree of 23/06/1993)
• 🔴 06/1998 → 09/1998 – Drought – clay shrink-swell (RGA) (prefectoral decree of 27/12/2000)
• 🔴 01/2002 → 06/2002 – Drought – clay shrink-swell (RGA) (prefectoral decree of 25/08/2004)
• 🔵 10/2008 – Floods (prefectoral decree of 09/02/2009)
• 🔵 06/2010 → 06/2010 – Floods (prefectoral decree of 21/06/2010)
• 🔵 11/2011 → 11/2011 – Floods (prefectoral decree of 18/11/2011)
• 🔵 10/2012 → 10/2012 – Floods (prefectoral decree of 10/01/2013)
• 🔵 01/2014 → 01/2014 – Floods (prefectoral decree of 31/01/2014)
• 🔵 11/2014 → 11/2014 – Floods (prefectoral decree of 17/02/2015)
• 🔵 11/2016 – Floods (prefectoral decree of 26/06/2017)
• 🔴 07/2017 → 09/2017 – Drought – clay shrink-swell (RGA) (prefectoral decree of 18/09/2018)
• 🔵 10/2018 → 10/2018 – Floods (prefectoral decree of 26/11/2018)
• 🔵 10/2018 → 11/2018 – Floods (prefectoral decree of 26/02/2019)
• 🔴 07/2019 → 09/2019 – Drought – clay shrink-swell (RGA) (prefectoral decree of 15/12/2020)
• 🔵 11/2019 → 11/2019 – Floods (prefectoral decree of 28/11/2019)
• 🔵 12/2019 → 12/2019 – Floods (prefectoral decree of 12/12/2019)
• 🔴 04/2022 → 09/2022 – Drought – clay shrink-swell (RGA) (prefectoral decree of 03/04/2023)
• 🔴 04/2023 → 06/2023 – Drought – clay shrink-swell (RGA) (prefectoral decree of 18/06/2024)
• 🔵 10/2024 – Floods (prefectoral decree of 15/12/2024)
• 🔵 05/2025 → 05/2025 – Floods (prefectoral decree of 27/05/2025)

Expert reading: 6 droughts and 15 floods. Clusters (several decrees close together) flag up crisis periods – the summer of 2022-2023 is the best recent example. An owner whose damage dates from a covered period has a solid Cat Nat file; outside a covered period, the way forward is an action against the seller.

Local rainfall: why your cracks often appear a year or two after the drought

Annual rainfall recorded on the Vidauban weather grid (Open-Meteo data):

• 2019: 1,000 mm · 2020: 530 mm · 2021: 691 mm · 2022: 562 mm · 2023: 598 mm · 2024: 1,015 mm
• Average over the period: 732 mm/year, driest year: 2020 (530 mm)
• Three consecutive deficit years: 530 mm in 2020, 562 mm in 2022, 598 mm in 2023
• Then a rebound to 1,015 mm in 2024

Remember this principle, it explains almost all the cracks we are shown in Vidauban: first the drought dries out the clay at depth – shrinkage, first cracks – then the return of the rain rehydrates the ground at a stroke, causing swelling and differential movement. If you live in a villa built between 1970 and 2000 on shallow foundations (most of the local housing stock), do not be surprised if the cracks appear 12 to 24 months after a dry summer rather than during it.

Cracks in Vidauban: the signs that should make you call an expert

• A stair-step crack, passing through the wall, wider than 2 mm
• A crack that evolves: fit a plaster tell-tale or a marker-pen reference point and recheck 2-3 months apart
• Associated damage: doors and windows sticking, tiles splitting diagonally, render blistering and coming away
• A house on clay soil, a tree close by, failed drainage

With 6 drought prefectoral decrees on the commune’s tally, as soon as you build up two or three of these signs, do not launch into re-rendering or filling before a survey: you risk masking evolving damage, and losing a piece of evidence if you later need to claim compensation or sell.

Buying or selling a cracked house in Vidauban: what you risk, what you can do

Between the recent drought decrees and the volume of transactions underway, quite a few properties are changing hands with damage kept quiet. If you discover cracks after the purchase, you have two possible routes:

• Hidden defect (article 1641 of the Code civil): serious cracks, invisible at the viewing, predating the sale → you can claim a reduction in the price or cancellation of the sale, within 2 years of discovery
• Fraud (dol) (article 1137): the seller knew and concealed the damage → you can claim cancellation and damages, within 5 years; the commune’s GASPAR decree then becomes supporting evidence in your file

Before pursuing either route, have your damage dated by an expert, then appoint a property-law solicitor (avocat) for the proceedings.

How a drought/clay survey unfolds in Vidauban

• Technical visit: crack survey and classification, crack-width measurements, functional damage
• Local context: clay zone, the commune’s natural disaster declaration (Cat Nat) history (6 drought decrees), recorded dry periods
• Costing of works: underpinning, injections, drains – with several scenarios depending on your budget
• A written report you can pass directly to your insurer or your solicitor

Independent expert, with no ties whatsoever to any building contractor. Request a visit in Vidauban – see also our complete RGA and Cat Nat guide for 06, 83 and 13.

Soil surveys on clay ground: what the regulations say

The requirement for a prior geotechnical survey has applied since 1 October 2020 (ELAN law, art. 68); the new exposure map of 1 July 2026 widens its scope. This obligation, stemming from ELAN law no. 2018-1021, article 68 (decree no. 2019-495 of 22 May 2019), applies to Vidauban (medium exposure in the BRGM classification).

• What it changes for building: the soil survey is no longer an option – the ELAN law makes it compulsory in an exposed zone for every sale of building land and every construction contract. Adapted foundations, ground treatment, drainage arrangements: the specifications flow directly from the survey.
• What it changes when buying a recent property: ask whether the survey was carried out and which specifications were applied. A house built without following the geotechnical recommendations on clay soil is a medium-term cracking risk.
• What it changes when selling: the absence of a survey on a property built before the obligation is not a defect in itself – but if damage appears, a seller who knew about it and concealed it exposes themselves to an action for fraud (dol).
• The link with the data above: Vidauban combines medium exposure with a documented history of drought decrees. Building or buying here without checking the nature of the ground means building on a known and measured risk.

Cassini Expertise handles these files: compliance checks between geotechnical specifications and execution, damage surveys on clay ground, counter-expertise. Request a consultation.

Frequently asked questions

Is Vidauban among the clay risk zones?

Yes. The Alpes-Maritimes and the Var are very broadly covered by the clay shrink-swell (RGA) hazard (BRGM mapping, viewable on georisques.gouv.fr). In Vidauban, the 6 drought decrees recognised in GASPAR confirm the risk is not theoretical: it has already materialised several times, and your house can be affected even with no visible crack today.

Can my cracked house in Vidauban be compensated under the natural disaster scheme?

Only if your damage can be tied to a period covered by a decree (the latest recognised periods: 2000, 2004, 2018, 2020, 2023, 2024) and if you declared the loss within 30 days of publication of the decree. If not, the action against the seller remains – and it is the dating of the damage through a survey that then becomes decisive for your file.

Can the figures quoted on this page be checked?

Yes: the decrees come from the GASPAR database (Journal officiel, open data sets, 2025 update), the rainfall from Open-Meteo weather archives for the Vidauban grid. Cassini Expertise merely compiles them, without adjustment – you can cross-check them yourself before contacting us.

Where do the rains stand? (as at 04/10/2026)

In the commune: recent rain (3 days ago). Rainfall over the last 30 days: 21 mm, against roughly 54 mm expected at this time of year – a 61% deficit.

A sustained deficit over this window, especially in the growing season, often precedes by a few weeks the drop in the water table shown above: it is the first signal owners can track themselves, before any cracks appear.

Drought right now (as at 05/10/2026)

In the commune: recent rain (4 days ago). Rainfall over the last 30 days: 21 mm, against roughly 56 mm expected at this time of year – a 62% deficit.

A sustained deficit over this window, especially in the growing season, often precedes by a few weeks the drop in the water table shown above: it is the first signal owners can track themselves, before any cracks appear.

Drought right now (as at 12/10/2026)

In the commune: recent rain (3 days ago). Rainfall over the last 30 days: 91 mm, against roughly 64 mm expected at this time of year – a 42% surplus.

A sustained deficit over this window, especially in the growing season, often precedes by a few weeks the drop in the water table shown above: it is the first signal owners can track themselves, before any cracks appear.

Where do the rains stand today? (as at 19/10/2026)

In the commune: recent rain (1 day ago). Rainfall over the last 30 days: 98 mm, against roughly 73 mm expected at this time of year – a 34% surplus.

A sustained deficit over this window, especially in the growing season, often precedes by a few weeks the drop in the water table shown above: it is the first signal owners can track themselves, before any cracks appear.

When was the aquifer last this low?

The reference piezometric station for the area (002LDFT) has been monitoring the aquifer since 2000 – 26 years of records. As at 02/10/2026, the average level over the last thirty days is 141.35 m NGF (French ordnance datum). Across the whole record, the aquifer has spent only 7.2% of its time below this level: a very low level, rarely reached in the station’s history.

• Last equivalent episode: 04/01/2024 – 2.7 years ago
• Frequency: 26 similar episodes recorded since 2000, i.e. an annual return on average – in hydrologists’ language, a rare event
• Historic minimum: 141.1 m NGF, reached on 01/10/2000

This long memory changes how the risk is read: a low level is not just a weather episode, it is an event whose frequency is known. For a house on clay, it is this frequency that tells you the probability of fresh settlement – and therefore how urgent the precautions are.

Find out more: Article 1641 of the Civil Code and the hidden defects warranty (garantie des vices cachés), explained.

Survey carried out by Frédéric Faucouneau, independent building expert – Antibes, Alpes-Maritimes (06), Var (83), Bouches-du-Rhône (13). Find out more

📅 Last updated 06/11/2026 - Cassini Expertise, independent building expert – departments 06, 83 and 13.